Inelastic pulsed neutron scattering measurements on YBa2Cu3O6.95 single crystals indicate that the sample has a distinct a-b plane anisotropy in the oxygen vibrations. The Cu-O bond-stretching-type phonons, which are suspected to interact strongly with charge, are simultaneously observed along the a and b directions due to a 7-meV splitting arising from the orthorhombicity, even though the sample is twinned. The bond-stretching LO branch with the polarization along a (perpendicular to the chain) loses intensity beyond the middle of the zone, indicating branch splitting as seen in doped nickelates, with the second branch being located at 10 meV below. The mode along b has a continuous dispersion. These modes show temperature dependence, which parallels that of superconductive order parameter, suggesting significant involvement of phonons in the superconductivity of this compound.


Materials Science and Engineering

Keywords and Phrases

barium; copper; oxygen; yttrium; anisotropy; conductance; crystal structure; dispersion; elementary particle; neutron scattering; oxygen affinity; polarization; temperature dependence; vibration

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version

Final Version

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© 2003 American Physical Society (APS), All rights reserved.

Publication Date

01 Jan 2003